Fiber product and process of making same



Patented ay 3, 193 2 on cmcaao, rumors mean raonuc'r am) PnocEss 0F NoDrawing.

well as a desirable stillness.

The process I have invented utilizes in the main commercial equipmentreadily available on the open market and no drawing thereof is required.

\ 4 There are many methods for preparing fibers for use with myinvention and I will describe one particular procedure which I havefound well suited in the case of wood fiber prepared from wood waste. Itshould be understood that many modifications of this practice are stillapplicable without departing from the scope o my invention.

Assuming that the raw materials employed in this case is wood waste suchas saw mill refuse, the pieces are passed through a shredder such as ahammer type and reduced to a mass of coarse fibers somewhat resemblingstraw. I have found it desirable to pass these fibers through twoshredding operations using a considerable amount of fiber and a smallamount of water, so that the fibers are rubbed upon each other duringthe shredding process. longer length fiber and reduces the amount ofshorter or cut fibers.

After leaving the second shredder the fibers are preferably conveyed ata fairly high density to a Glafiin. FromtheClafiin the fibers aredeliveredto a beater or equivalent device.

In the beater a portion of the product, which I will designate forpurposes of convenience as soluble pitch, is added and the beatingcontinued, preferably for one or two hours in order to thoroughlydisseminate the soluble pitch throughout the entire fiber mass.

This action causes more of the Application filed February 24, 1980.Serial No. 431,057.

This operation is ordinarily-carried out with a low concentration offibers and a large amount of water. For example, three to six per centof fibers by weight, the balance being water, isa common condition whichI find gives very satisfactory results. It should be understood ofcourse that the nature of the fiber, the product beingproduced and manyother factors control this ratio and I do not wish to be limited to anyspecific figure. a

After the beating has been completed and the soluble pitch-thoroughlydisseminated throughout the mass, the mixture is preferably renderedslightly acid, as'for example,

by adding alum or other salts having an acid reaction,

This results in. the precipitation of the pitch from the material I havecalled soluble pitch. The pitch thus precipitated is attached to thefibers, rather firmly and uniformly in the form of small particles.

The mixture is then delivered to a sheet forming device of the typeknown as Fourdrinier, a rotary machine or an Oliver form 4 If it isdesired to make a hard. board the next step in my process is to re-.

move instead of ninety-five percent of the water, somewhere in theneighborhood of sixty percent of the water and then place the partiallydried sheet between steam heated platens. Pressure is then appliedto'the platens rangin from 500 to 1000 pounds per square inch. Thecombined effect of pressure and temperature is to produce a hard densesheet theexact thickness being determined by the amount and kind of rawma terial used and the amount of pressure and temperatures to which itis subjected.

During the pressing operation, moisture is driven from the centralportion of the board to the surface where it is converted .into vapor.As a result, there is a steady flow of moisture from the central portionof the board to the surface. This flow carries with it small particlesof fiber, loose portions of Inns and other pitch or size and variousmaterials. These fine materials form a relatively hard homogeneous masswhich acts as a cement or filler for the surface of the board and givesit water resistant properties. Filling the interstices with thiscementin material also increases the strength of the oard as well asmaterially improves its appearance. Such a board has a hard glassysurface which is strong, water-resisting, durable and usually a goodinsulator against electricity.

Referring to the substance which I have designated as soluble pitch, itshould be noted that I may produce this material from various tars,pitches or resins. I have found that there are a very wide; range ofmaterials suitable for this purchase. For example coal tar or coal tarpitch, water gas tar, by-product coke, oven tar, wood tar, from wooddistillation and many of the pitches and tars which result as aby-product from industrial heat treatments, are available.

For example in certain cases petroleum pitch, obtained from thedistillation of fuel oil, is suitable and I have also used asphalt andvarious so-called petroleum products such as mineral wax, etc.

The material selected should be placed in a liquid condition, preferablyif its character permits by the application of a gentle heat or if thisis not feasible by the addition of the solvent such as benzine, naphtha,gasoline, kerosene, alcohol, ether, etc. Obvlously the exact solventmust be selected with a knowledge of the material used and inasmuch ascommercial solvents for various pitches and tars are well known,myinvention is not restricted to the-specific solvent which is used. Ifnecessary I may add a I slight amount of solvent and heat as in somecases a combined action is helpful. I

Having reduced the pitch or tar to a liquid or pasty form I next add oneof the fatty acids, as for example, stearic acid, oleic acid, etc. Theclass of fatty acids is well known and I do not wish to limit myinvention to any particular acid or group.

After thoroughly incorporating the fatty acids with the pitch in pastyform a small percentage ofbasic material is added. A wide range of basesmay be employed for this purpose. For example ammonia, caustic soda,causitc potash, soda ash, various amines and substituted bases such astriethanolamine etc., may beemployed.

I have found also that such alkaline materials as borax, etc.,may alsobe. employed.

The base chosen must be selected with a view to the properties desired.I have found very excellent results are obtained by the use ofsubstituted amines such as triethanol- 'be coke oven tar oleic acid 15%,triethanolamine 5%.

It should be understood that the above ratio is typical and aconsiderable variation may be made from the percentages given withoutdeparting from the spirit'of this invention. In many cases it ispossible to materially reduce the percentages of the fatty thepercentage acid and of bases, increasing of tar or pitch.

After the addition of the triethanolamine or other bases to the mixtureof pitch and fatty acid, the material is then thoroughly stirred ormixed, preferably with the application of gentle heat, as for example atemperature of 160 to 200.

In some cases where the tar or pitch shows a decidedly acid reaction, itmay be desirable to thoroughly neutralize such acidity before theaddition of the oleic acid and the basic material. This is not alwaysabsolutely essential, but of greatest importance in cases whereappreciable amounts of free mineral acid may be present. If the acidreacmay be reduced or possibly even eliminated. V

The mixture of tar or pitch, fatty acid and base may be treated in ahomogenizer, but in many cases such elaborate treatment is unnecessary.

The resultant mixture is now ready to be added to water .in which itwill promptly form a rather permanent suspension on t orough mixing orstirring. The mixture should preferably be added to warm water at atemperature of around 100 or slightly higher.

Thorough stirring and mixing should follow the addition. The watershould preferably be either neutral or slightly alkaline in reaction.Acid reaction in the water is to be carefully avoidedat this stage ofthe process.

The amount of water'added' depends upon the subsequent treatment. Ingeneral, I have found that a ratio equivalent to from one part in twentyto one part in ten by weight, I

gives good results. That is to say, approximately one pound of liquidtar or pitch with additions toabout one gallon of water.

- This mixture may then be added in a beater or equivalent agitatingdevice to the fiber suspension which has been previously described. Iprefer to shred the fibers underthe conditions outlined previously inthis specifica tion, under a spray of intensely hot water and ifpossible maintain the suspension of fiber quite hot until it reaches thebeater or equivalent device. For example the water sprayed onto thefibers during the shredding process may to advantage be in theneighborhood of 200 F. Subsequent steps in the process will perhaps coolthe water and fibers to 150 or thereabouts. At this temperature theaddition of the tar or pitch mixture shouldtake place. Although manyvariations of these temperatures are possible without departing from thespirit of this invention.

After theaddition of the tar or pitch mixture to the fibers thematerials should be intimately commingled. This can be accomplished byoperating the beater or equivalent device for a period of an hour orthereabouts.

After the pitch or tar has been thoroughly distributed through thesolution a mate rial having an acid reaction should be added. I havefound that aluminum sulphate, alum, calcium chloride, various saltswhich dissociate giving an acid reaction, or various dilute acids may beemployed. I prefer a ma terial such as alum or aluminum sulphate,however- The addition of the acid material appears to destroy theemulsion of the pitch or tar causing it to adhere rather uniformly tothe fiber particles. This is best accomplished by continuing the actionof the beater or the stirring device during the addition of the acidmaterial. This reaction takes place rather promptly and under ordinaryconditions ten or fifteen minutes beating is sufiicient although theexact time depends of course on the materials used, the temperature,effectiveness of the beater and other'obvious factors.

Having now precipitated the pitch or tar. onto the various fibers theresultant material is formed in a sheet in any of the well known ways.For example, the material may be passed over a Fourdrinier, a sheet maybe formed on a rotary filter or ordinary rotary vacuum machines may beemployed. The sheet thus formed is then passed through a dryer where themoisture is materially reduced. In the manufacture of a thick board thesheet formed on the Fourdrinier or rotary would ordinarily be one andone-half to two inches in thickness. Such a sheet would conbe pressedbetween felt strips on a continuous press removing 10 to 20% of thewater.

Such a sheet may then be passed through a roller dryer in which theamount of water would be reduced to perhaps 50%. All of thesepercentages are merely approximate as will be of course variabledepending on the amount of water in the sheet and the desiredcharacteristics of the finished product. Fifteen to twenty minutes givesexcellent results.-

In order to provide ready escape for the steam contained in the board ascreen or other foraminous structure may be placed between the board andone of the platens.

Under the influence of heat and pressure the pitch or tar which has beenuniformly distributed throughout the mass of materials, softens andforms a cementing medium which securely binds the fibers together. Theresulting product is very strong, water resisting and is a goodinsulator of electricity. Obviously the characteristics of the resultingprodnot will vary with the amount and nature of the tar or pitch. If aflexible product is desired I preferably select a rather plastic tar orpitch and limit the quantity to two or three percent of the fiber of theboard. If a hard rigid product is desired I preferably select a pitch ortar having a high melting point and one which is hard and rigid atordinary roomtemperatures. I also increase the quantities verymaterially sometimes using twenty percent or moreof pitch or tar. Itwill be understood that my invention is not confined to any specificpercentages as different results may be obtained by varying thepercentages and character of the raw material.

In this specification I have used the term pitch or tar in a generalsense to indicate inert organic materials which are frequently wasteproducts. The term condensation product may perhaps be used in a generalsense to designate this'class of substance. For example the tar or pitchresulting from the distillation of wood, coal or other organic materialsis unquestionably a condensation product. Similarly water gas tar,asphalt, etc., are condensation products. In the same way the productproduced by subjecting linseed oil to heat or to oxidation is acondensation product. I have used all of these various classes ofmaterials including the .condensation formed from phenols andformaldehyde. I have also used the condensation product formed bycombining tung oil with rosin. Each of "these products give a differentresultant product and require obvious variations in preparation. In thefollowing claims I am using the term condensation product to indicatethe class of materials described in this specification.

It should be understood that I do not claim asmy invention the additionof li uid tar or pitch to aboard already formed. am aware that it hasbeen proposed to add tar or pitch in liquid form, but such an additiondoes not 19 penetrate the fibers thoroughly or uniformly. Such aprocedure also requires extremely large quantities of pitch or tar andthe distribution is such that there is a decided tendency for theproduct to become sticky when subjected to heat or service.

On the other hand, the process which I have invented requires much lessbinder, gives an entirely uniform distribution of the binder throughoutthe thesheet without permitting sufiicient quantities of thecondensation product to collect at anyone point to cause the sheet tobecome soft or sticky.

' The results of the uniform distribution in which the condensationproduct is attached to each fiber is far superior to the former methodand also permits the surface of the board is strong and durable withoutbeing subject to subsequent softening under the conditions of practicaluse.

40 It is frequently desirable to use a mixture of several condensationproducts, thus com-- bining certain characteristics of each.

By the term drying oils used in claims 7 and specificat ons, I intend todesignate those products which are used'in the'arts to form a firm hardfilm as in paints and similar products.

These oils include linseed oil, tung oil,'mix- ,tures of tung oil,rosin, etc. The exact-type of oil used will determine the variouscharacteristics of the resultant product.

The preparation of drying oils, their blending, heat treating and otheroperations .are well understood in the art and form no part of thisspecification. I I Having now fully described my invention, what I claimas new and wish to "secure by Letters Patent in the United States, is asoofollows:

I 1. A fiber sheet, consisting of a felte'd'mass of. fibers cementedinto Jan aggregate by a precipitated emuls on of oil.

2. A fiber sheet consisting of i felted mass, of fibersattached'together' y a substantially said fibers in said water meuniformly distributed containing drying oil.

3. In a fiber sheet a binder consisting o uniformly distributed productcontaining dryin oil and-rosin attached to said fibers.

cipitating such emulsion on said fibers, and then forming a felt fromsaid fibers drying "rarity water from said felt, and finally hardeningsaid oil.

5, The process of making a fiber sheet which consists in firstdispersing said fibers ina solution, second adding to said solution anemulsion containing drying oil, third precipitating such emulsion onsaid fibers, and then forming a felt from saidfibers (1 ing said felt,and finally hardening the 011 in said felt by heat. I

6, The process of making a fiber sheet which consists in firstdispersing said fibers in a solution, second addin to said solution anemulsion containing drying oil, third precipitating such emulsion o'nsaid fibers, and

then forminga felt from said fibers and drying said felt and oxidizingsaid oil while at an elevated temperature.

7. The process of making a fiber sheet,

wh ch consists in first dispersing said fibers in a water solution,second brushing said fibers while in suspension, third addin an emulsioncontaining drying oil to said fi rs -while in solution, fourthprecipitating said emulsion by adding'a material having an acidreaction, fifth felting said fibers, and finally drying, and oxidizingsaid oil at an elevated temperature.

8. The process of making a fiber sheet,

which consists in first dispersing said fibers ina water solution, asecond brushing said fibers while in suspension, third addin an emulsioncontainin drying oil to said bers while in solution, fourthprecipitating said emulsion by adding a material having an acidreaction, fifth felting said fibers and finally drying and pressing saidfelt and oxidizing said oil while at an elevated tempera.- ture.

9. The process of making a hard board which consists in separating woodfibers and suspending them in a water medium, second adding an emulsioncontaini drying oil to ium and-intimately mixin third precipitating saidemulsion, fourth orming a felt from said fibers carryingsaid preciitated emulsion and finally pressing saidelt at an elevated temperature,thereby hardening said oil.

10. The process of making a fiber; sheet which consists in sus ndingfibers in a water medium, second a; ding to. said suspended fibers anemulsion consisting of drying oil and gum dispersed by an alkalinematerial,

third neutralizing said solution thus precipitating the emulsion uponsaid fibers, fourth felting said fibers and pressing and drylng saidfelt, and finally drying said drying oil.-

water medium, adding an emulsion contain-- ing a condensation product ofdrying oil and a substituted amine, bringing said mixture of fibers andemulsion to an acidcondition and finally felting, drying and pressingthe resultant product, and hardening said drying oil.

14. A fiber sheet having a mixture of condensation product of hardeneddrying oiland fatty acid distributed substantially uniformly throughoutits mass.

15. The process of making a fiber sheet which consists in firstsuspending a mass of fibers in a water medium, second mixing drying oiland fatty acid with an alkaline mate-' rial, third adding said mixtureofsaid drying oil to said fibers and uniformly mingling the two. fom'thprecipitating said drying oil and fatty acid upon said fiber and finallyfelting said fiber and submitting said felt to the action of heat andpressure, thereby removing water fromsaid felt and hardening said dryingoil.

16. The processof making a fiber sheet which consists in firstsuspending a mass of fibers in a water medium, second mixing acombination including drying oil and fat acid with an alkalinematerial,third adding said mixture including drying oil to said fibersand uniformly mingling the two, fourth precipitating said mixtureincluding drying oil and fatty acid upon said fiber and finally feltingsaid fiber and submitting said felt'to the action of heat,therebypermanently fixing said drying oil.

17. A fiber sheet consisting of a felted mass of fibers containing asubstantially uniformly distributed binder formed from a mixture of tungoil, linseed oil and rosin in a polymerized condition.

18. A sheet consisting of amass of cellulose fibers through which isdistributed a binder containing drying oil and rosin in the polymerizedconditio WILLIAM A. DARRAH.

